Disk drive with nonvolatile memory having multiple modes of operation

Abstract

A hybrid disk drive, i.e., a disk drive with two types of permanent storage media (conventional disk media and nonvolatile memory, such as flash memory), uses its nonvolatile memory in operational modes other than the power-save or “standby” mode wherein the disks are spun down. In a first additional mode, called a “performance” mode, one or more blocks of write data are destaged from volatile memory (the disk drive's write cache) and written to the disk and simultaneously one or more data blocks of write data are destaged from the volatile memory and written to the nonvolatile memory. In a second additional mode, called a “harsh-environment” mode, the disk drive includes one or more environmental sensors, such as temperature and humidity sensors, and the nonvolatile memory temporarily replaces the disks as the permanent storage media. In a third additional mode, called a “write-inhibit” mode, the disk drive includes one or more write-inhibit detectors, such as a shock sensor for detecting disturbances and vibrations to the disk drive. In write-inhibit mode, if the write-inhibit signal is on then the write data is written from the volatile memory to the nonvolatile memory instead of to the disks.

1. A disk drive comprising:
 a rotatable recording disk for the storage of data from a host computer; 
 a data controller adapted for connection to the host computer for transferring data from the host computer to the disk and capable of receiving a write inhibit signal; 
 volatile memory connected to the controller for temporary storage of data prior to transfer to the disk; and 
 nonvolatile memory connected to the controller; 
 
       the controller having a first mode of operation that includes writing data to the nonvolatile memory when the disk is not rotating, and a second mode of operation that includes (a) writing data to the nonvolatile memory when the disk is rotating and (b) destaging write data from the volatile memory to the nonvolatile memory if the controller detects a write-inhibit signal. 
     
     
       2. The disk drive of  claim 1  wherein the data from the host computer comprises blocks of write data to be written to the disk, and wherein the second mode of controller operation includes storing multiple blocks in the volatile memory and destaging a first block from the volatile memory to the rotating disk and a second block from the volatile memory to the nonvolatile memory. 
     
     
       3. The disk drive of  claim 2  wherein destaging blocks of write data from the volatile memory to the nonvolatile memory includes destaging according to a first-in first-out (FIFO) procedure. 
     
     
       4. The disk drive of  claim 2  wherein destaging blocks of write data from the volatile memory to the rotating disk includes destaging according to a disk rotational positioning optimization (RPO) procedure. 
     
     
       5. The disk drive of  claim 1  wherein the disk drive further comprises an environmental sensor for signaling the data controller, and wherein the second mode of controller operation includes destaging write data from the volatile memory to the nonvolatile memory when the data controller detects a signal from said environmental sensor. 
     
     
       6. The disk drive of  claim 1  wherein the second mode of controller operation includes, after the write data has been destaged to the nonvolatile memory if the controller detected a write-inhibit signal, transferring the write data from the nonvolatile memory to the disk if the controller does not detect a write-inhibit signal. 
     
     
       7. The disk drive of  claim 1  further comprising a shock sensor coupled to the controller for generating the write-inhibit signal. 
     
     
       8. The disk drive of  claim 1  wherein the disk includes concentric data tracks for the storage of data, wherein the disk drive includes a head for writing data to the data tracks and a servo control system coupled to the head for measuring a position error signal (PES) of the head on a data track, and wherein the controller detects a write-inhibit signal when the value of the PES exceeds a predetermined value for a predetermined time period. 
     
     
       9. A magnetic recording disk drive comprising:
 a rotatable magnetic recording disk for the storage of blocks of write data from a host computer, the disk having a plurality of concentric data tracks; 
 a write head movable across the surface of the disk for writing the blocks of write data on the disk; 
 a data controller adapted for connection to the host computer for transferring the blocks of write data from the host computer to the write head for writing on the disk; 
 volatile memory connected to the controller for temporary storage of the blocks of write data prior to writing on the disk; and 
 nonvolatile memory connected to the controller; and 
 
       wherein the controller comprises logic for executing method acts of:
 in a standby mode of operation wherein the disk is not rotating transferring blocks of write data from the host computer to the volatile memory and then destaging blocks of write data from the volatile memory to the nonvolatile memory; and in a non-standby mode of operation wherein the disk is rotating transferring blocks of write data from the host computer to the volatile memory, destaging at least a portion of the blocks of write data from the volatile memory to the nonvolatile memory, and thereafter transferring blocks of write data from the nonvolatile memory to the disk; wherein the non-standby mode of controller operation is a performance mode including storing multiple blocks in the volatile memory and destaging a first block from the volatile memory to the rotating disk and a second block from the volatile memory to the nonvolatile memory according to a first-in first-out (FIFO) procedure. 
 
     
     
       10. The disk drive of  claim 9  wherein the volatile memory comprises DRAM and the nonvolatile memory comprises flash memory. 
     
     
       11. A disk drive comprising:
 a rotatable recording disk for the storage of blocks of data from a host computer; 
 a data controller adapted for connection to the host computer for transferring blocks of data from the host computer to the disk; 
 volatile memory connected to the controller for temporary storage of blocks of data prior to transfer to the disk; and 
 nonvolatile memory connected to the controller; 
 
       the controller having a first mode of operation that includes writing blocks of data to the nonvolatile memory when the disk is not rotating, and a second mode of operation that includes storing multiple blocks of data in the volatile memory and destaging a first block from the volatile memory to the rotating disk and a second block from the volatile memory to the nonvolatile memory, wherein destaging blocks from the volatile memory to the nonvolatile memory includes destaging according to a procedure selected from (a) a first-in first-out (FIFO) procedure and (b) a disk rotational positioning optimization (RPO) procedure. 
     
     
       12. A disk drive comprising:
 a rotatable recording disk for the storage of data from a host computer; 
 a data controller adapted for connection to the host computer for transferring data from the host computer to the disk; 
 an environmental sensor for signaling the data controller; 
 volatile memory connected to the controller for temporary storage of data prior to transfer to the disk; and 
 nonvolatile memory connected to the controller; 
 
       the controller having a first mode of operation that includes writing data to the nonvolatile memory when the disk is not rotating, and a second mode of operation that includes (a) writing data to the nonvolatile memory when the disk is rotating and (b) destaging write data from the volatile memory to the nonvolatile memory when the data controller detects a signal from said environmental sensor. 
     
     
       13. A magnetic recording disk drive comprising:
 a rotatable magnetic recording disk for the storage of blocks of write data from a host computer, the disk having a plurality of concentric data tracks; 
 a write head movable across the surface of the disk for writing the blocks of write data on the disk; 
 a data controller adapted for connection to the host computer for transferring the blocks of write data from the host computer to the write head for writing on the disk; 
 volatile memory connected to the controller for temporary storage of the blocks of write data prior to writing on the disk; and 
 nonvolatile memory connected to the controller, and 
 
       wherein the controller comprises logic for executing method acts of:
 in a standby mode of operation wherein the disk is not rotating transferring blocks of write data from the host computer to the volatile memory and then destaging blocks of write data from the volatile memory to the nonvolatile memory; and in a non-standby mode of operation wherein the disk is rotating transferring blocks of write data from the host computer to the volatile memory, destaging at least a portion of the blocks of write data from the volatile memory to the nonvolatile memory, and thereafter transferring blocks of write data from the nonvolatile memory to the disk; wherein the non-standby mode of controller operation is a performance mode including storing multiple blocks in the volatile memory and destaging a first block from the volatile memory to the rotating disk and a second block from the volatile memory to the nonvolatile memory according to a disk rotational positioning optimization (RPO) procedure. 
 
     
     
       14. A magnetic recording disk drive comprising:
 a rotatable magnetic recording disk for the storage of write data from a host computer, the disk having a plurality of concentric data tracks; 
 a write head movable across the surface of the disk for writing the write data on the disk; 
 a data controller adapted for connection to the host computer for transferring the write data from the host computer to the write head for writing on the disk; 
 an environmental sensor for signaling the data controller; 
 volatile memory connected to the controller for temporary storage of the write data prior to writing on the disk; and 
 nonvolatile memory connected to the controller; and 
 
       wherein the controller comprises logic for executing method acts of:
 in a standby mode of operation wherein the disk is not rotating transferring write data from the host computer to the volatile memory and then destaging write data from the volatile memory to the nonvolatile memory; and in a non-standby mode of operation wherein the disk is rotating transferring write data from the host computer to the volatile memory, destaging at least a portion of the write data from the volatile memory to the nonvolatile memory, and thereafter transferring the write data from the nonvolatile memory to the disk; wherein the non-standby mode of controller operation is a harsh-environment mode including destaging write data from the volatile memory to the nonvolatile memory when the data controller detects a signal from said environmental sensor. 
 
     
     
       15. A magnetic recording disk drive comprising:
 a rotatable magnetic recording disk for the storage of write data from a host computer, the disk having a plurality of concentric data tracks; 
 a write head movable across the surface of the disk for writing the write data on the disk; 
 a data controller adapted for connection to the host computer for transferring the write data from the host computer to the write head for writing on the disk, the controller being capable of receiving a write inhibit signal; 
 volatile memory connected to the controller for temporary storage of the write data prior to writing on the disk; and 
 nonvolatile memory connected to the controller; and 
 
       wherein the controller comprises logic for executing method acts of:
 in a standby mode of operation wherein the disk is not rotating transferring write data from the host computer to the volatile memory and then destaging write data from the volatile memory to the nonvolatile memory; and in a non-standby mode of operation wherein the disk is rotating transferring write data from the host computer to the volatile memory, destaging at least a portion of the write data from the volatile memory to the nonvolatile memory, and thereafter transferring the write data from the nonvolatile memory to the disk; wherein the non-standby mode of controller operation is a write-inhibit mode including destaging write data from the volatile memory to the nonvolatile memory if the controller detects a write-inhibit signal and, after the write data has been destaged to the nonvolatile memory if the controller detected a write-inhibit signal, transferring the write data from the nonvolatile memory to the disk if the controller does not detect a write-inhibit signal. 
 
     
     
       16. The disk drive of  claim 15  further comprising a shock sensor coupled to the controller for generating the write-inhibit signal. 
     
     
       17. The disk drive of  claim 15  wherein the disk drive includes a servo control system coupled to the head for measuring a position error signal (PES) of the head on a data track, and wherein the controller detects a write-inhibit signal when the value of the PES exceeds a predetermined value for a predetermined time period.